Electric-field-induced local and mesoscale structural changes in polycrystalline dielectrics and ferroelectrics.
Electric-field-induced local and mesoscale structural changes in polycrystalline dielectrics and ferroelectrics.
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DOI：
10.1038/srep14678
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发表时间：
2015-10-01
影响因子：
4.6
通讯作者：
Jones JL
中科院分区：
文献类型：
--
作者：
Usher TM;Levin I;Daniels JE;Jones JL
电介质/铁电体对电场的原子尺度响应是其功能的核心。本文介绍了一种揭示多晶材料在场作用下局部原子结构变化的原位表征方法。该方法采用原子对分布函数（pdf），由x射线总散射确定，该散射取决于相对于应用场的方向，以探测从亚-Ångstrom到几纳米的长度尺度上的结构变化。PDF对局部离子位移及其短程顺序敏感，这是相对于其他技术的关键独特性。该方法应用于具有代表性的铁电体BaTiO3和Na½Bi½TiO3以及介电体SrTiO3。对于Na½Bi½TiO3，结果显示了一个突如其来的场诱导单斜向菱形相变，伴随着局部Bi位移的有序和纳米级铁电畴的重定向。对于BaTiO3和SrTiO3，在pdf中观察到的局部/纳米级结构变化分别由压电晶格应变和离子极化率主导。
The atomic-scale response of dielectrics/ferroelectrics to electric fields is central to their functionality. Here we introduce an in situ characterization method that reveals changes in the local atomic structure in polycrystalline materials under fields. The method employs atomic pair distribution functions (PDFs), determined from X-ray total scattering that depends on orientation relative to the applied field, to probe structural changes over length scales from sub-Ångstrom to several nanometres. The PDF is sensitive to local ionic displacements and their short-range order, a key uniqueness relative to other techniques. The method is applied to representative ferroelectrics, BaTiO3 and Na½Bi½TiO3, and dielectric SrTiO3. For Na½Bi½TiO3, the results reveal an abrupt field-induced monoclinic to rhombohedral phase transition, accompanied by ordering of the local Bi displacements and reorientation of the nanoscale ferroelectric domains. For BaTiO3 and SrTiO3, the local/nanoscale structural changes observed in the PDFs are dominated by piezoelectric lattice strain and ionic polarizability, respectively.